During the past year, major emphasis has been placed on therapeutic studies of hereditary angioedema (HAE). A group of patients is being followed for signs of EACA toxicity and is on long-term therapy with this drug. During the year, a second drug was evaluated as an agent which might be useful in therapy. Provera, high dose progesterone therapy, of HAE proved ineffective in therapy. A third hormonal agent is now under double-blind study. This drug is the impeded androgen, Danazol. A method of approach to the problem of dental surgery of these patients has been developed. Two units of fresh-frozen plasma are given on the day prior to major dental work. Six patients underwent seven major procedures under this therapy without any attacks of oral swelling. This same group of patients underwent 23 previous procedures with 18 attacks of marked swelling and 4 life-threatening HAE attacks.